Parkways -- Oregon -- Portland Metropolitan Area, Urban planning -- Oregon -- Portland Metropolitan Area, Greenways -- Oregon
A brief history and overview of the 40 mile loop and other regional trails in and around the Portland, Oregon area, as well as Metro's 1992 Metropolitan Greenspaces Master Plan and proposed future extensions.
Axtell, Sharon (2002). "The Landscape: 40 Mile Loop & Regional Trails: Park it Here," Metroscape, Summer 2002, pages 4-5. Published by Institute of Portland Metropolitan Studies, Nohad A. Toulan School of Urban Studies & Planning, Portland State University.